Deodorizing Process Batch :The Batch Deodorizing is done in a Deodorizer - A Cylindrical Vessel with Dished Ends at Top and Bottom with sufficient vapour space to handle the vapours.

It is provided with Heating coils, Vacuum Connection, oil charging and Discharging lines, open steam injecting coils, sampling line, sight and light glasses, etc.

Process :The Deodorized oil is kept under vacuum after removing all the air inside. The Bleached oil is charged to the required level. Heating is started. Dry saturated open steam is injected at the predetermined rate. However care should be taken to see that the vacuum does not fall. The Adjustment should be done till the equilibrium conditions are attained. The temperature is raised to 1000 C when the Booster ejector is connected to improve the vacuum. The Temperature is raised to the required level depending on the oil/fat and the material of construction of the Deodorizer. In case of M.S. the temperature should not be above 190 C. If SS is used then the temperature can go upto 230 0C. However the vacuum in this case should never be less than 756mm of mercury. Otherwise the oil will be damaged due to Heat in the presence of Air. While charging the oil, required quantity of citric acid is also sucked in which acts as a metal scavenger protecting the oil from contamination with the metal traces from the body of the vessel.

After the required time of Deodorisation, sample is taken and tested for the taste and odour. The oil is then dropped to the cooler also under vacuum where it is cooled by cooling oils with cooled water to the required temperature. The cooled oil is filtered through polishing filter presses to produce crystal clear colourless and odourless refined oil.

Principle of Deodorizing Process
Certain chemical substances called Aldehydes and Ketones are responsible for the odour in the Oils/Fats. Added to this, the Bleaching Process also imparts it's own odour to the oil. Fortunately all these odour imparting substances can be removed by steam distillation under reduced pressure(vacuum) and high temperature while the oil remains intact due to it's higher boiling point. Using this property, steam is used to carry away these substances as vapour under vacuum and high temperature and the same condenses in a vessel called Fatty Acid Catcher. These Distillates can be removed from the Catcher and sold to soap Makers.

Continous Deodorizing
This has gained popularity due to it's inherent advantages.
As explained earlier, Deodorizing process is done at very high temperature and at reduced pressure to prevent damage of oil. While high temperature can be attained by Thermic Fluid Heating System in place of steam which is quite costly, for Vacuum System, steam is the only medium used for getting the high Vacuum of 756 MM of Mercury or 4 MM absolute power. Mechanical Pumps in combination with Steam Booster Ejector System also are found inadequate. It is in this context that the Continuous Deodorizers have become popular because of the enormous saving in Steam. For a Batch Process, the quantity of vapour to be handled is far too high necessitating huge steam Ejector System requiring very high quantity of Steam where as in Continuous Deodorizing System due to the low vapour load at any time the vacuum system requirement is moderate with reduced requirement of Steam. This reduces the cost of steam requirement very much. Apart from this, the Heat Recovery facilities provided in the Continuous system also reduce the Fuel Cost. Moreover flexibility of operation is possible to strike the optimum operating conditions.